Rolling of metal billets



Feb. 3, 1970 J, MARCOVITCH ROLLING 0F. METAL BILLETS Filed Aug. 14. 1967 4 Sheets-Sheet 1 bymwme Mam Mmecor/rw/ 6y rJW Feb, 3, 1970 MARCOVITCH 3,492,349

ROLLING OF METAL BILLEIS Filed Aug. 14, 1967 4 Sheets-Sheet 4 Awa rae (/9c 00 Aliza wzzw United States Patent 3,492,849 ROLLING F METAL BILLETS Jacob Marcovitch, Johannesburg, Transvaal, Republic of South Africa, assignor to Rotary Profile Anstalt, Vaduz,

Liechtenstein Filed Aug. 14, 1967, Ser. No. 660,386 Claims priority, application Republic of South Africa, Aug. 22, 1966, 66/5,031 Int. Cl. B21b 19/00 US. Cl. 72-75 Claims ABSTRACT OF THE DISCLOSURE The invention concerns apparatus for rolling metal rod (including tube) to reduce it, and contemplates the passage of the rod through an elongated throat that is lined with working formations that operate on the rod, the working formations being rotated relatively to the rod about at least one axis that is substantially parallel to the direction of elongation of the throat. Relative rotation takes place between the rod and the throat during the operation. The working formations may be undulations in the surfaces of rollers extending along the throat or small rolling elements contained within the bore which defines the throat.

This invention relates to the rolling of rod to reduce it in cross-section. The rod may be solid or tubular.

In conventional practice, the rolling of rod for this purpose is carried out in successive stages or passes. In each pass, the rod is fed through a throat defined between two rollers which have their axes inclined substantially at right angles to the direction of advance of the rod, the surfaces of the rollers being profiled to vary the cross-section of the rod by a relatively small amount. As many as 13 or passes may be used, depending on the total reduction or variation required. Some of the passes may, for example, be round-oval passes or diamond-oval passes, the names corresponding to the cross-sectional shape of the rod before and after the pass. Because of the large areas of contact between rod and rollers during each pass, the mill requires high-power driving equipment which must be duplicated at successive stages.

These factors make conventional rolling mills expensive and bulky.

The object of the invention is to provide novel compact apparatus for rolling rod which permits extensive reduction in cross-section in a single pass, so that a finished or nearly finished article may be produced rapidly and economically.

According to the invention, apparatus for reducing rod consists of means defining an elongated convergent throat, working formations lining the throat along its length, the working formations being rotatable about at least one axis, which axis is substantially parallel to the direction of elongation of the throat, means to pass a rod through the throat, to be rolled by the working formations, and means to cause rotation of the rod relatively to the throat during its passage through the throat. Further according to the invention the final Working formations define between them a substantially cylindrical throat to produce a round rod.

In some forms the throat is defined by at least two, and preferably three, rollers that are mounted with their axes substantially parallel to the direction of elongation of the throat, the working formations being undulations such as annular or helical scrolls in the surfaces of the rollers.

In other forms, the working formations are small work rollers rotatable about their axes and arranged to trace out a scrolled path around the rod as it advances through the throat and simultaneously rotates within it; or to be skewed and running in parallel grooves.

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In some cases it is necessary to feed the rod through the throat by a force feed. In other cases, the arrangement of the working formations is such that they draw the rod through the throat without external aid. To bring about the required rotation of the bar relatively to the throat, the rod is in some cases rotated by external means while the throat is kept stationary, or the rod may be held against rotation while the throat itself is rotated. There may be various combinations of the aforementioned cases.

Various embodiments are described below with reference to the accompanying drawings, in which:

FIGURE 1 is a semi-schematic longitudinal view through one form of rolling apparatus employing at least two rollers with circumferentially grooved surfaces;

FIGURE 2 shows a view similar to that of FIGURE 1 of a second form of rolling apparatus having helical scrolls;

FIGURE 3 is a similar view showing an embodiment with rollers set in parallel grooves in a bore;

FIGURE 4 shows an embodiment similar to that of FIGURE 3 but with a divided bore;

FIGURE 5 shows another form of apparatus with small work rollers lining a bore of a casing and seated in helical grooves in the bore;

FIGURES 6 to 8 show alternative forms of rollers for use with some of the embodiments described above;

FIGURES 9 to 11 show semi-schematic end views of possible arrangements for some of the embodiments described above; and

FIGURE 12 is a side View of a scroll made by the machine of the invention.

In FIGURE 1, two or more rollers 12, 14 define a throat between them. The roller 12 is shown in section. They are tapered and their axes are inclined towards each other to define between the rollers a converging throat. The rollers are formed on their surfaces with working formations which are a series of annular grooves 16. A rod 18 is offered to the mouth 20 of thethroat and its propulsion through the throat is aided by an external force feed indicated schematically at 22. The rollers are rotated in the same direction and, as the rod 18 is propelled through the throat, it in turn rotates and has imposed on it a spiral formation, as seen in the drawing. The grooves 16 are preferably spaced progressively further apart in the direction of convergence of the throat, to accommodate the progressive lengthening of the rod, so that the helical formation imposed on the rod becomes of progressively larger pitch. In the final part 23 of the throat, the lands 24 are smooth and parallel, so that the rod emerges from the throat as a cylinder. Once it has emerged, the passage of the billet may be assisted by pulling on the rod by means indicated schematically at 28. The operating conditions will determine whether the helix imposed on the billet is single or multi-start, but since the terminal part 23 of the throat is smooth and parallel, this is of no consequence as the spirals rolled into the rod are smoothed out and disappear.

However, the grooves may be provided right up to the ends of the rollers (by eliminating the lands 24), in which case the end product Will be a helix of increasing pitch, as seen in FIGURE 12. Such a product may be cut into lengths and put to such uses as the rotors of pumps.

FIGURE 2 illustrates a modified form of apparatus in which the rollers 13, 15 are tapered and formed with identical helical scrolls 30 but Which are in phase With respect to each other. The axes of the rollers are parallel to each. The rollers act as Archimedean screws, which, once they have gripped the end of the billet 19, draw it through the throat and, in the process, impose on it annular formation of steadily decreasing diameter but increasing space. Forced feed is unnecessary. The scrolled grooves terminate near to the end of the throat to leave smooth 3 parallel lands 32, as in FIGURE 1. The final product is a cylinder, as in the case of FIGURE 1.

In FIGURE 3, a cylindrical casing 34, rotatable about its axis, has a stepped bore 36, formed with parallel grooves 38 which are progressively further apart and which accommodate a series of small work rollers 40 that are sufficiently loosely held to enable them to skew; that is to take up a position in which their axes are inclined to the axis of the rod. The rollers 40 are preferably held in cages (not illustrated). A rod 21 is pushed through the throat by means indicated schematically at 33, while the casing 34 is rotated, to impose on the rod a helix, as in the case of FIGURE 1. A pull on the reduced rod is exerted by means indicated at 35. The end product is a round rod if, as shown, the end rollers 44 are parallel to roll out the helix in the billet. This embodiment has the advantage over the embodiment of FIGURES l and 2 that the grooved and tapered casing 34 is easier to fabricate than the rollers of FIGURES 1 and 2, and that the series of small rollers 40, 44 is readily replaceable.

FIGURE 4 shows a modified form of the apparatus of FIGURE 3. The casing 34 of FIGURE 3 is divided into three sections, 34a, 34b and 34c, but retains the stepped bore grooves 38, rollers 40, 44 and'propulsion means 33 and 35. The divided casing permits the sections 34a, 34b and 340 to be rotated at different speeds, and thus to harmonise with the formation of the helix and increasing axial speed of the bar 21.

Generally speaking. if the rollers have annular grooves and are arranged with their axes parallel, the billet must be forced-fed. If the same rollers are obliquely arranged, (i.e. slightly otf-parrell) the mill itself will draw the rod through the throat, and force-feeding will be either unnecessary or merely auxiliary. With helically grooved rollers, whether parallel or oblique, the rollers themselves provide the driving power to propel the billet through the throat, or at least contribute most of the force required.

It will be apparent that the rollers will be called upon to resist displacement by very large forces as the billets advance through the throat. To counter this, back-up rollers may be provided at intervals by discontinuing the grooves or scroll-s for a short distance to provide smooth surfaces on which the backup rollers bear, as will be described in connexion with FIGURES 10 and 11.

A further development is seen in FIGUR'ES 5. Here, a cylindrical casing 50 with a tapered bore 52, is formed with an internal scroll 54 of substantially sawtooth profile but with the apex 56 of the groove cavity-rounded; and within the scroll is located a series of balls 58 which line the throat provided by the bore. A billet 57 offered to the big end of the throat is nipped by the balls and entrained through the throat while the casing 50 is rotated. The natural elongation of the billet 57 as it is reduced in diameter. The end of the scroll is parallel, as shown at 60, to produce an end product which is a cylindrical rod, as seen at 62. It is an advantage to exert a continuous axial force, such as a pull on the issuing rod by means indicated schematically at 64.

The balls of FIGURES 5 may be rep-laced by elements such as shown in FIGURES 6 to 9. In FIGURES 6 and 7 the elements have diametrally opposed stub axles 66 which roll on the lands of the scroll. In FIGURES 8 and 9, the elements are barrel-type rollers which are engaged in a scroll of suitable profile.

Whatever the nature of the elements, they may be recirculated, and it is also possible to provide for the throat to be divided up into sections in each of which elements are recirculated. This construction may be used with advantage to cool the elements which, if they have to traverse the whole length of the throat, may become overheated.

In those embodiments in which the throat is defined between juxtaposed rollers, there may be two such rollers 27, 27 as in FIGURE 10, a system which has the advantage that he diameter of the small end of the throat can be as small as one may wish. However, it may be necessary to provide guides to maintain the billet 51 in a straight path. A multi-roller system, that is three or more roller-s collectively defining the throat is an attractive system because the billet 51 is fully supported, and because the load on individual rollers is correspondingly diininished; but the minimum throat dimension is correspondingly increased. FIGURE 11 shows such a system with back-up rollers 68 supporting the juxtaposed rollers 29 surrounding the billet 53; and, of course, backup rollers may be provided in the two-roiler system to FIGURE 10.

The above description has assumed that the rod or billet is solid. It is, however, possible to treat a tubular billet in the apparatus of the invention, the reduction serving to diminish or close down the bore by inward collapse of the billet as it advances.

I claim:

1. Apparatus for rolling rod to reduce it comprising a housing, a bore through the housing forming an elongated convergent throat, rollers lining the throat along its length, the rollers being rotatable respectively about axes which are substantially parallel to the direction of elongation of the throat, means to pass a rod through the throat to be rolled by the rollers, and means to cause rotation of the rod relative to the throat during its passage through the throat.

2. The apparatus of claim 1 in which the housing is divided, and including means to rotate the housing sections at different relative speeds.

3. The apparatus of claim 1 in which the rollers are mounted in a helical groove in the bore, and are adapted to advance along the bore with passage of the rod through the throat.

4. The apparatus of claim 3 in which the rollers are balls.

5. Apparatus as claimed in claim 1 wherein the rollers are balls.

6. Apparatus as claimed in claim 5 wherein the balls in the housing at the end portion of the throat circumscribe a cylindrical space.

7. Apparatus as claimed in claim 1 wherein the rollers are nonspherical in shape.

8. Apparatus as claimed in claim 7 wherein the rollers in the housing at the end portion of the throat are cylindrical and are of greater axial length than the remaining rollers.

9. Apparatus for reducing the outside diameter of an elongated workpiece having a cylindrical outer surface: the apparatus comprising a throat having an inlet and an outlet and through which a workpiece may pass, and within the throat convex working means which are spaced from one another in any one axial plane of the throat on one side of the axis of the throat to provide a plurality of undulations along the length of the throat in such plane, the distance radially of the throat between the crests of adjacent undulations being small at the inlet to the throat and increasing toward the center of the throat and then becoming small again toward the outlet from the throat.

10. Apparatus as claimed in claim 9 wherein the distance of the crests of the undulations from the axis of .the throat decreases from the inlet of the throat to the outlet thereof and the pitch of the undulations increases toward the outlet of the throat.

References Cited UNITED STATES PATENTS 576,822 2/1897 Pilkington 72100 767,314 8/1904 Sandner 7277 2,358,307 9/1944 Dewey 72100 LOWELL A. LARSON, Primary Examiner US. Cl. X.R. 

